Arriving at the destination conveniently and safely is significantly important for the consumer group who own automobiles. Various types of automobiles or vehicles have become prerequisite traffic means or transporting equipment in the modern society. As a result, people are paying more and more attention to the safety of driving a vehicle.
One of the factors that affects the safety of driving is the functionality and proper operation of a vehicle's components (such as the braking system, tires, and ignition system), which is the most important link. In terms of tires, factors that affect the safety include tire pressure and tire temperature in addition to the grooves of the tire surface. As such, the tire pressure and/or temperature detection are crucial for a vehicle.
For example, if the tire pressure is 25% lower than the normally required tire pressure over a long period of time, the tire tends to have a dramatic temperature rise that may result in a blowout when the vehicle is moving at a high speed. If the tire pressure is too high or insufficient, it will cause damage to the tires.
Accordingly, should the tire pressure be 25% higher than a standard tire pressure value, the usable life of the tire will be shortened by 15%-20%, and when tire pressure is 25% lower than the standard value, the usable life of the tire shortens by 30%. Properly inflated tires not only have enhanced performance and safety in use, but also save more fuel and have prolonged tire life.
However, according to statistics, 20% of vehicles that are currently being used have insufficiently inflated tires. Moreover, tire temperatures also have an important influence on safe driving. The higher the tire temperature is, the lower the tire strength is. That is, tires with high tire temperature are more easily deformed. Moreover, tire wear increases by 2% when the tire temperature rises by 1° C.
Only when the tire pressure is at the right amount can the tire achieve its optimal performance. When the tire pressure is too high, the fraction of the tire when rolling becomes small. However, because the contact area between the tire and the ground is shortened, the middle of the tire is worn out quickly. Because the tire's surface tension expands, it creates damages as well as cracks. On the other hand, when the tire pressure is insufficient, the fraction of the tire when rolling becomes great, gas consumption increases, and the wear and tear on both sides of the tire increases relatively. As such, it increases the tire temperature and causes the surface or ply of the tire to exfoliate easily. When the tire temperature is overheated, a blow out may occur.
To ensure safe driving, various types of tire pressure monitoring systems have been developed. Some prior art references teach the incorporation of sensors, either to the tire proper or in proximity thereof, for measuring an operational parameter of the tire. Once the parameter is measured, it is transmitted to a terminal at a remote location, such as for example a maintenance facility, or to a monitor fixedly mounted to the vehicle.
A number of prior art devices have attempted to solve the problem of improperly inflated vehicle tires. Typically, these devices tend to monitor tire parameters, such as temperature and pressure, and provide an indication to the vehicle operator if any of the vehicle tires are improperly inflated or a potential safety hazard exists due to severe under inflation. Many of the prior art devices provide a remote sensor within each of the tires in addition to a transmitter for transmitting a signal to a centrally located receiving unit. However, some prior art devices have succumbed to at least one of the many varied challenges imposed upon a sensor subjected to the incredibly harsh operating environment of a vehicle tire.
A typical vehicle operating environment is not particularly amenable to the transmission and reception of digital or analog signals. Since some of the transmitter is often located entirely within a vehicle tire, powered by a battery separate from the vehicle battery, the receiver must be especially sensitive to the detection of relatively weak signals present in an electrically noisy milieu. Furthermore, the various electrically conductive components found on a typical vehicle may facilitate electrical communication but tend to hinder radio wave transmissions.
Another significant problem associated with the transmitter disposed upon or within the vehicle tire is that rotation of a transmitting antenna induces a “Doppler frequency shift” in the transmitted signal if the antenna is not oriented with its centre of mass along the axis of rotation of the vehicle tire. Thus, systems which utilize a valve stem of the tire as the transmitting antenna must provide complex detection circuitry to compensate for the Doppler shift. Alternatively, such systems may dramatically increase the redundancy of transmissions since much of the information will be filtered out as noise. Moreover, high rotational speed or revolution of the tire wheel may lead to inconsistency of signal transmission. Thus, inconsistent transmission and relatively weak signals may lead to loss of information or false information with regard to the tire pressure/temperature conditions of the vehicle.
In view of these and other shortcomings, it is desirous to provide a wireless tire monitoring device adapted to be detachably mounted to a valve stem of the vehicle tire, such that it provides a simple and effective device that provides both economy of manufacture and simplicity/convenience of use, and yet resists unfavourable weather conditions, dirt or debris contamination, while enabling the device to function reliably under conditions adverse to wireless transmissions, such as frequency shift induced by rotation of the wheel or Doppler shift. The present invention also facilitates prolonged periods of power consumption, and yet substantially reduces assembly and maintenance costs. The wireless tire monitoring device of the present invention and its combination of elements thereof will be described and/or exemplified in the detailed description.